NEC 78K0 User Manual page 56

15
SP SP15 SP14 SP13 SP12 SP11 SP10 SP9
The SP is decremented ahead of write (save) to the stack memory and is incremented after read (restored) from
the stack memory.
Each stack operation saves/restores data as shown in Figures 3-14 and 3-15.
Caution Since RESET input makes the SP contents undefined, be sure to initialize the SP before using
the stack.
SP
SP
SP
SP
SP
SP
56
CHAPTER 3 CPU ARCHITECTURE
Figure 3-13. Format of Stack Pointer
Figure 3-14. Data to Be Saved to Stack Memory
(a) PUSH rp instruction (when SP = FEE0H)
FEE0H
FEDEH
(b) CALL, CALLF, CALLT instructions (when SP = FEE0H)
FEE0H
FEDEH
(c) Interrupt, BRK instructions (when SP = FEE0H)
FEE0H
FEDDH
User's Manual U16227EJ2V0UD
SP8 SP7 SP6 SP5 SP4
FEE0H
FEDFH Register pair higher
FEDEH
Register pair lower
FEE0H
FEDFH PC15 to PC8
FEDEH PC7 to PC0
FEE0H
FEDFH
PSW
FEDEH PC15 to PC8
FEDDH PC7 to PC0
0
SP3 SP2 SP1 SP0